The erythrocytic entry- and exit-mechanism of Aegyptianella pullorum Carpano, 1928.

The erythrocytic entry- and exit-mechanisms of Aegyptianella pullorum were investigated and characterized by scanning (SEM) and transmission electron microscopy (TEM) using for TEM ruthenium red as a marker of the red cell plasmalemma. The scanned Aegyptianella preparations produced static evidence of an endocytosis followed by an erythrocytic vesiculation as the possible mode of entrance of initial bodies into erythrocytes. The presence of ruthenium red only coating the membrane around the parasitophorous vacuole during the whole invasive process and the complete absence of the stain inside the host cell indicate that the entry of aegyptianellas is accomplished by invagination of the host cell plasmalemma and is not preceded nor followed by its breakage, furthermore unequivocally proving the intracellular parasitism of A. pullorum during its reproductive cycle. One possible mode of exit of initial bodies from parasitized erythrocytes appeared to be the invasive mechanism in reverse order, an exocytosis. Generally, however, the affected erythrocytes are parasitogenically injured, resulting in release of the parasites into the plasma and, subsequently, in host cell lysis.